Reactive capture and electrochemical conversion of CO2 with ionic liquids and deep eutectic solvents

Ionic liquids (ILs) and deep eutectic solvents (DESs) have tremendous potential for reactive capture and conversion (RCC) of CO2 due to their wide electrochemical stability window, low volatility, and high CO2 solubility. There is environmental and economic interest in the direct utilization of the captured CO2 using electrified and modular processes that forgo the thermal- or pressure-swing regeneration steps to concentrate CO2, eliminating the need to compress, transport, or store the gas. The conventional electrochemical conversion of CO2 with aqueous electrolytes presents limited CO2 solubility and high energy requirement to achieve industrially relevant products. Additionally, aqueous systems have competitive hydrogen evolution. In the past decade, there has been significant progress toward the design of ILs and DESs, and their composites to separate CO2 from dilute streams. In parallel, but not necessarily in synergy, there have been studies focused on a few select ILs and DESs for electrochemical reduction of CO2, often diluting them with aqueous or non-aqueous solvents. The resulting electrode-electrolyte interfaces present a complex speciation for RCC. In this review, we describe how the ILs and DESs are tuned for RCC and specifically address the CO2 chemisorption and electroreduction mechanisms. Critical bulk and interfacial properties of ILs and DESs are discussed in the context of RCC, and the potential of these electrolytes are presented through a techno-economic evaluation.

The Baeyer–Villiger Oxidation of Cycloketones Using Hydrogen Peroxide as an Oxidant

Baeyer–Villiger oxidation can synthesize a series of esters or lactones that have essential application value but are difficult to be synthesized by other methods. Cycloketones can be oxidized to lactones using molecular oxygen, peroxy acids, or hydrogen peroxide as an oxidant. Hydrogen peroxide is one of the environmental oxidants. Because of the weak oxidation ability of hydrogen peroxide, Bronsted acids and Lewis acids are used as catalysts to activate hydrogen peroxide or the carbonyl of ketones to increase the nucleophilic performance of hydrogen peroxide. The catalytic mechanisms of Bronsted acids and Lewis acids differ in the Baeyer–Villiger oxidation of cyclohexanone with an aqueous solution of hydrogen peroxide as an oxidant.

Reviewing and screening ionic liquids and deep eutectic solvents for effective CO2 capture

CO₂ capture is essential for both mitigating CO₂ emissions and purifying/conditioning gases for fuel and chemical production. To further improve the process performance with low environmental impacts, different strategies have been proposed, where developing liquid green absorbent for capturing CO₂ is one of the effective options. Ionic liquids (IL)/deep eutectic solvents (DES) have recently emerged as green absorbents with unique properties, especially DESs also benefit from facile synthesis, low toxicity, and high biodegradability. To promote their development, this work summarized the recent research progress on ILs/DESs developed for CO₂ capture from the aspects of those physical- and chemical-based, and COSMO-RS was combined to predict the properties that are unavailable from published articles in order to evaluate their performance based on the key properties for different IL/DES-based technologies. Finally, top 10 ILs/DESs were listed based on the corresponding criteria. The shared information will provide insight into screening and further developing IL/DES-based technologies for CO₂ capture.

1-Butyl-3-methylimidazolium bromide functionalized zeolites: nature of interactions and catalytic activity for carbohydrate conversion to platform chemicals

In this study, 1-butyl-3-methylimidazolium bromide ([BMIM]Br) functionalized zeolites were synthesized by a facile ship-in-bottle strategy and utilized for the carbohydrates conversion to platform chemicals (5-hydroxymethylfurfural and furfural).

Enhanced Gas Separation through Nanoconfined Ionic Liquid in Laminated MoS2 Membrane

Two-dimensional (2D) materials-based membranes show great potential for gas separation. Herein an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), was confined in the 2D channels of MoS₂-laminated membranes via an infiltration process. Compared with the corresponding bulk [BMIM][BF₄], nanoconfined [BMIM][BF₄] shows an obvious incremental increase in freezing point and a shift of vibration bands. The resulting MoS₂-supported ionic liquid membrane (MoS₂ SILM) exhibits excellent CO₂ separation performance with high CO₂ permeance (47.88 GPU) and superb selectivity for CO₂/N₂ (131.42), CO₂/CH₄ (43.52), and CO₂/H₂ (14.95), which is much better than that of neat [BMIM][BF₄] and [BMIM][BF₄]-based membranes. The outstanding performance of MoS₂ SILMs is attributed to the nanoconfined [BMIM][BF₄], which enables fast transport of CO₂. Long-term operation also reveals the durability and stability of the prepared MoS₂ SILMs. The method of confining ILs in the 2D nanochannels of 2D materials may pave a new way for CO₂ capture and separation.

Photocatalytic degradation of imidazolium ionic liquids using dye sensitized TiO2/SiO2 composites

The photodegradation efficiency of imidazolium ILs reach 95% with DCQ-TiO₂/SiO₂ as the photocatalyst under simulated solar light.

Ionic liquid@MIL-101 prepared via the ship-in-bottle technique: remarkable adsorbents for the removal of benzothiophene from liquid fuel

Ionic liquids were firstly synthesized in a pore of metal–organic framework via a ship-in-bottle technique; and the obtained IL@MOF showed a remarkable reusability/stability in the adsorptive desulfurization of model fuel.